Process for the manufacture of esters



A. A. BACKHAUS.

PROCESS FOR'THE MANUFACTURE OF ESTERS.

WPPLICATION FILED 0CT.1I,1919- Patented Aug. 15, 192 2.

forward -in the drawing, I have siren ram "as sets,

ARTHUR BAQKHAUS, 0F BALTIMORE, MARYLAND, ASSIGNOR TO U. S. TNDUS 'E ALCOHOL CO., A CORPORATION 0F"WEST VIRGI1\T,IA. I

PROCESS FOR THE MANUFACTURE 'OF a citizen of the United States, residing at' Baltimore, in the State of Maryland, have invented a certain new and useful Improvement in Processes for the Manufacture of Esters, of which thefollowing is'a specification. o

My invention relates particularly to a process of producing esters of various kinds in an advantageous manner, butrelates especially to the production of ethyl acetate.

The object of my invention is to provide a process with which esters may be made in an expeditious manner while avoiding loss 'of heat as 'far as possible, decreasing the length of time for esterification, and pro;

ducing a product which is substantially free,

from acids. A further object is to provide such a process in which there is an effective separation of the materials driven oif from the esterification chamber in the form of a vapor, and a return to' said chamber of only those materials which have not yet been esterified, while the vaporized ester passes for subsequent condensation. Again, one of the objects'of my invention is to expedite th'e'operation ofthe process by avoiding the return of any of the vaporized ester, and thus obviating the tendency of any such returned ester to tion of further ester.

Further o jects of my invention will appear from the detailed description thereof contained hereinafter. v

While my invention is capable of being carried out in many different ways, for the inafter, and while it is capable of being ing drawing, in which; i

The figure is a diagrammatic representation of an apparatus which may be used in accordance with my invention.

Assuming that my invention is-applied to the production of ethyl acetate, :as shown rovided an esterification chamber 1 havln'g a valved inlet pipe for vinegar 2 leading from'a vinegar storage receptacle 3, Connected to the tank; 1, there is also a valved inlet pipe 4 for sul-- phuric acid communicating with a sulphuric inhibit the produc- Specification of Letters Patent. Patgnted Aug, 15, 1922, Application filed October 11, 1919. Serial No. 329,925.

acid storage receptacle 5. Again, attached to said tank 1-, there is a valved inlet pipe 6 for alcohol leading from an alcohol storage receptacle 7 Vinegar, sulphuric acid, and alcohol are fed into the chamber 1 in the proportion of .33 parts by weight ,of sulphurlc acid having astrength of 50 to 66 I 1%., to 10 parts of weight of vinegar having a strength of 8% acetic acid and 8/10 part by weight of ethyl alcohol having a strength of 95%. These materials are heated by means of aclosed coil steam pipe 8 in the bottom of the" chamber 1.

prised of ethyl acetate, alcohol, and water,

The vapors, ,fo'rmed in the chamberl which are com-' as well as a li'ttle acetic acid are conveyed by a vapor pipe 9 to arectification column 10 comprising aiplurality of pans 11 having overflow pipes 12 and hooded vapor conducting pipes 13'. The column 10 is maintained at a temperature of substantially 70 0., at

the top thereof, so that a constant boilingmixture of ethylacetate, alcohol, and water containing approximately 83% ethyl acetate,

9% alcohol, and 8%- water, pass out of the topuoi thesame through a vapor outlet pipe 14 while the residual materials entering the column 10 return by a trappedpipe '15 to the esterification chamber 1. The vaporized mixture of ethyl acetate, alcohol,.a nd water pass from the pipe 14 into a de hlegmator 16. comprised of tube sheets "1 and 17* carrying tubes '18 cooled by a current of water flowing through inlet and outlet pipes '19 and 20 and the liquid formed-in the dephlegmator passes by a trapped pipe 21- back to the column 10 in, order to seal the pans therein while the uncondensed va .ors pass by alpipe 22 to a condenser 23 his is comprised of tube sheets 24 and 24 carrying tubes 25 cooled by a current of water flowing through inlet and outlet pipes26 and 27. The condensate flows away by a pipe 28through a tail box 29 to any suitable point for storage. I

The esterification in the chamber 1 is con-' tinued until the e'sterification isv complete,

after which the alcohol, sulphuric acid, and I water, are withdrawn by a valved pipe 30 from the chamber 1, and forced through a pipe 31 by a pump 32 to a storage receptacle 33 fromwhich the liquid is drawn ofi' by a alcohol concentratlng column 35 constructed thesame as the colum1 1 10, except that in valved trapped pipe 34, and conveyed to an I i a.

the bottom thereof, there is a perforated pipe 36 for supplying live steam, and at the bottom of the column 35 there is a drawoff pipe 37 leading to an overflow bottle 38. having a vapor outlet'pipe 39 and a trapped discharge pipe 40 for the water and S111" p'huricacid. The vapors of alcohol having a strength of 80% or higher pass outby a vapor pipe 41 to a dephlegmator 42 constructed in the same manner as the dephlegmator 15and having a trapped return pipe 43 leading to the top of the column 35; A pipe 44 conveys the uncondensed vapors from the dephlegmator 42 to a condenser 45- constructed the same as the condenser 23" from which the condensate is conveyed by a pipe 46 to the alcohol storage tank'7.

'The operation of my invention will bereadily understood from the preceding description.

In general, however, it will be understood that the vinegar, alcohol, and sulphuric acid which are supplied to the chamber 1 from time to time inthe proportions above given are heated by the steam coil, and the vapors of alcohol, ester, and water with a little acetic acid pass therefrom into the column 10 which serves to return to the esterification chamber all of the vaporized materials, except the constant boiling mixture of alcohol, ethyl acetate, and water 'hereinabove referred to, which is secured as a condensate and passes out through the tail box 29. The, ethyl acetate thus obtained is substantially entirely freed fromacetic acid by the columnnlO, and furthermore, the yie d of ethyl acetate per unit of time is very much increased owing to the fact that the este'rification is not impeded bythe return of ethyl acetate to the chamber 1. When the mixture of vinegar and alcohol has been completely esterified, the remaining alcohol, sulphuric Iacid, and water are withdrawn to the storage chamber 33 from which they are supplied tothe alcohol concentrating column 35 which serves to separate alcohol having a high degree of stren h from the remaining water and sulphuric acid, the alcohol being condensed andcollected in the alcohol storage tank? for further use in the process, while th water and sulphuric acid are discharged as Waste materials from the apparatus. v

It ,will be understood that other acids and other alcohols may be used instead of the acetic acid or vinegar and the ethyl alcohol,

as for example, methyl alcohol, formic acid,

butyric acid; that salts of such acids, as for example, calciumv acetate together with an additional quantity of a mineral acid as sul' phuric acid, may be used in place of the free acids; and that instead of the sulphuric acid;

another catalyst may be-used, as for ex ample, hydrochloric ac'd or some other organic acid, such as formic acid.

While I have described my invention above in detail, I wish it to be understood that many changes may be made therein without departing from the spirit thereof.

I claim:

1. The process of esterifying an alcohol and an' organic acid in the presence of a catalyst by the application of heat, characterized by' continuously distilling oii the ester formed and condensing out" from the distillate. vapors the major portion of the other vaporized constituents and contm'uously returning them't'o the sphere of reaction. a

v 2. The process of esterifying alcohol and acetic acid in the presence of sulphuric acld by the application of heat, characterized by continuously distilling off the ethyl acetate formed and condensing out from the distillate vapors the major portion of the other vaporized constituents and .continuously re-,

turning them to the sphere of reaction.

' 3. The proces's'of esterifying an alcohol and an organic acid in the presence of a catalyst'by the, application of heat, characreturning them to the sphere of reaction and drawing off the alcoholic aqueous acid, rectifying it and returning the alcohol to the'sphere of reaction. g

5. The process of ,making ethyl acetate comprising heating a mixture of alcohol; acetic acid, and suphuric acid, distilling oif the ester formed and leading the vapors into a rectifier to condense out the major part of the other constituents vaporized while withdrawing from the top of the rectifier the vapors of a constant boiling mixture of ethyl acetate, alcohol, and water.

6. The process of making ethyl acetate comprising heating-a mixture of alcohol, acetic acid and sulphuric acid, distilling-off the ester formed and leading the vapors into a rectifier to condense out the major part of the other constituents vaporized while Withdrawing from the-top of'the rectifier the vapors of a constant boiling mixture of ethyl acetate, alcohol, and water, and dephle'gmating the vapors and collecting the purified ethyl acetate.

7. The process of making ethyl acetate comprising heating a mixture of alcohol,

acetic acid and sulphuric acid, distilling of? the ester formed and leading the-vapors into a rectifier to condense out the major part of the other constituents vaporized While Withdrawing from the top of therectifier the the ester formed and leading the vapors into a rectifier to condense out the major part of the other constituents vaporized while withdrawing from the topiof the rectifier the vapors of a constant boiling mixture of ethyl acetate, alcohol and water, and removing from the sphere of reaction the alcoholic aqueous acid, rectifying it and returning the alcohol to the sphere of reaction.

In testimony that I claim the foregoing,

I have hereunto set my hand this 26 day of September, 1919.

/ ARTHUR A. BAGKHAUS. 

